The invention relates to a measurement device for control of the roll gap between the working rolls of a rolling or continuous casting and rolling mill, wherein the measurement device emits signals for process monitoring and control via at least one contact-free fitted sensor. The invention also relates to a process for the operation of a measurement device and its centering.
Measurement devices of the above type work under difficult conditions; the most common influences which can have damaging effects either alone or in combination are:
very coarse operation PA1 high throughput of coolant such as for example kerosene, liquid paraffins, water emulsions PA1 high ambient temperatures, up to around 80.degree. C. in cold rolling mills, up to around 200.degree. C. in hot rolling mills, even higher in continuous casting and rolling mills PA1 explosive media environment. PA1 a) Reduced barrel diameter of the working rolls, with double sensor arranged between the measurement surfaces PA1 b) Reduced barrel diameter of the working rolls, with sensors supported on a measurement bracket and arranged between a measurement surface and a supporting roll PA1 c) Reduced barrel diameter of the supporting rolls, with sensors supported on a measurement bracket and arranged between a measurement surface and a working roll PA1 d) Reduced barrel diameter of the working and supporting rolls, with double sensors supported on a measurement bracket and arranged between the measurement surfaces. Thus the roll gap can be measured via the measurement surfaces of the working and/or supporting rolls. PA1 reproducible measurement precision of around 1 .mu.m PA1 resistance to the working atmosphere, in particular thermal and chemical resistance PA1 accurate linear measurement over all distances PA1 no sensitivity to roll oil and dirt.
Hot rolling mills used as billet rolling mills produce strip thicknesses in the range from 4 to 60 mm, hot casting mills from 4 to 30 mm and cold rolling mills from virtually 0 to around 10 mm. Obviously these size ranges are given solely as examples.
The wearing working rolls are periodically reground by around 0.02 to 0.1 mm until their barrel diameter is only around 90% of the original diameter.
The strip thickness is affected in the fine range by the changes in rolling force, for example as a result of fluctuations in the hardness of the metal, incoming tolerance errors in the strip, fluctuations in the front tension forces, roll eccentricity and/or temperature changes.
In cold rolling mills in particular, the strip thickness tolerances are very tight. For example with a 0.2 mm thick strip, a tolerance of .+-.1.6 .mu.m is required. This necessitates a positioning accuracy of the working rolls of at least .+-.1 .mu.m.
Numerous measurement devices for controlling the roll gap are known.
CH,A 649012 describes a measurement device attached to a fixed part via a support. Attached to each of two lifting rods is a jaw, where one end of these jaws lies by spring pressure against the face of the reduced barrel diameter. A change in the roll gap is transferred to a measurement device via a pretensioned steel wire. Using this measurement device, the roll gap can be determined both analog and digitally.
DE,A 3512290 describes a measurement device which is arranged between two working rolls to be measured. In the area of both faces of the working rolls are arranged four supporting rolls in a star pattern. They lie against the barrel surfaces and are mounted to swivel on bearings on a measurement body. For mutual synchronization of the supporting rolls, these are connected mechanically to a toothed gear. The mechanical movement is converted into an electrical signal via a measurement sensor fitted in the measurement head.
U.S. Pat. No. 4,063,363 finally describes a measurement device which is screwed to a lower chock. A rod serves to guide two jaws which are pressed against the reduced diameter measurement surfaces by means of a spring. A linear emitter is arranged parallel to the roll gap adjustment, where this emitter measures the adjustment of the two resting jaws in direct relation to each other. The measurement device fitted at the face at both ends must be removed when the roll is changed.
The measurement device for a roll gap described in JP,A 62-214812 comprises two eddy current sensors 19, 20 which are mounted on a scissor-like spreadable carrier device. The roll gap is measured not in the area of the shortest spacing, on the roll plane, but indirectly using side auxiliary parameters.
DE,A 2503130 refers to an inductive, capacitive or laser-type measurement emitter which is arranged between two rolls and spring-mounted on a roller via an emitter holder. A sliding surface is formed on a roll pin so the measurement device does not work contact-free.
None of the known measurement devices for continuous monitoring of the roll gap during operation can satisfy all requirements of a modern rolling mill with regard to accuracy, function suitability, long life, simple mounting and economic operation.
The task facing the inventors was to create a contact-free measurement device of the type described above, which fulfils all the above requirements in a running rolling mill, measures the spacing between the working rolls in a simpler, more reliable and favorable cost manner and passes corrections to the adjustment element controls for adjustment of the roll gap. A process for operation and centering of such a measurement device should also be created.